This invention relates generally to image registration boards of the type used in photomechanical platemaking, duplication of negatives, and particularly to those used in page makeup (stripping) and exposing plates, proofs, or contact prints utilizing uniform reproducible alignment and registration such as in a "step-and-repeat" registration system.
U.S. Pat. No. 2,983,049 to Andrisani discloses a system for accurately positioning one or more negatives, flats, screens, plates, or masking sheets, and repositioning those items relative to a fixed reference point (or to one another) in discrete repeating increments. The system comprises a ruled board having evenly spaced index holes aligned with predetermined divisions of the rulers, and registration pins or offset spacers which may be received within those index holes. This ruled board is commonly referred to as a "step and repeat board," and the current state of the art in construction of step and repeat boards is shown and described in U.S. Pat. No. 4,987,686 to Ternes. The common practice is to space the flat (screen, plate, or masking sheet) a short distance away from the ruler and spacer, and apply a paper or thin plastic stripping tab overlapping both the spacer and flat (as shown in FIG. 15 of Andrisani '049 and FIG. 1 of Ternes '686.) The stripping tab has one or more holes to receive the pin of the spacer, and the opposing end is taped or adhered directly to the negative, flat, screen, plate, or masking sheet.
Once the negative, flat, screen, plate, or masking sheet has been aligned or registered as desired using a registration pin or spacer, this particular registration may be accurately reproduced at the same location or anywhere along the ruler (or on a remote board or apparatus having a corresponding line of holes with or without a ruler) using either the same or a distinct set of negatives, flats, plates, screens, or masking sheets and a similar set of registration pins or spacers.
Page makeup may be done on a light table, step and repeat board, or similar layout device, and then subsequently transferred to the platemaker. The platemaker might be a vacuum frame, or an automated step and repeat registration machine. Factors affecting whether a vacuum frame or step and repeat machine is used in platemaking are discussed in the above referenced parent application Ser. No. 07/780,739.
Images (individual or combined negatives or flats and any associated screens, plates, or masking sheets) may be transferred to an unruled image control board having spaced registration pins for exposure in a vacuum frame, such as shown in Harder '683. It is known to provide the image control board with compressible registration pins or compressible spacers, or in some cases the vacuum frames may have an integral registration system also including compressible registration pins. Compressible registration pins and spacers were similarly discussed in the above referenced parent application Ser. No. 07/780,739 and related continuation-in-part application Ser. No.07/917,456, now abandoned, thereof, with representative examples of compressible pins on image control boards and vacuum frames being shown in U.S. Pat. Nos. 4,977,683 to Harder and 3,634,009 to Van Dusen.
As shown particularly in the Andrisani '049 patent, it is known in the art to position the rulers and lines of indexing holes along all four side edges of the image layout area of a rectangular board, or alternately along two perpendicularly adjacent edges thereof in an L-shaped configuration.
However, in many applications such as the layout of large tabloid or newspaper sheets having gutters, ganging multiple or related images on a single board, color separations with extensive color bars or test strips, non-uniform or displaced register marks, or bleeds or masks that require additional pasteboard surrounding the image, conventional image registration boards are unsuitable.